Elements/Fields/Items

    Columns

    Records/Rows

    Tables

    Datatypes

    Primary Key

    Foreign Key

    Logical Data Model

    Oracle Tools

    DBA vs. Developer

Let us, first understand the basic definition of elements, fields, and items, columns, records, and rows, tables, datatypes, primary keys and foreign keys.

In this tutorial, we will use elements, fields and items interchangeably.

Also a record is the same as a row in a table.

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A field is the smallest unit in a table.

A record is a collection of fields.

A table is a collection of records.

A column must have a datatype.

A record can be added or inserted into a table.

A column in a row can be changed.

A record in a table can be deleted.

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A relationship between two tables can be established by defining primary or foreign keys.

A primary key is a unique identifier in a table.

A foreign key is a column that references to a primary key of another table.

To join two tables, you may use a “where clause” to set the table relationship between a primary and foreign keys.

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You use an "entity relationship diagram" or "logical data model" to establish the relationship between your entities.

In this diagram the relationship between the customer table and the order table, is established by their defined primary and foreign keys.

The foreign key of the order table references to the primary key of the customer table.

A customer can have one to many orders.

An order can refer to one and only one customer.

A primary key can be composed of more than one column.  We call it a composite index.

An example of a composite index is the Item table in this diagram.

Note.  The combination of two columns in the items table was used to create a primary key.  These two columns are "itemid" and "orderid".

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Here is another "entity relationship diagram".

Study these two diagrams and learn the relationships between each entity.  You are going to use all these tables in your Hands-On training during the entire tutorial.

You should have already created all these tables from your CD.

To learn more about creating your tables, you should follow the instructionsin the “Create iself schema” option on the “Readme First” sub-menu.

Remember, a collection of all these tables under the same or different schemas can be stored and maintained in a database.  So, a database is a collection of tables.

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The integrity, security, connectivity, performance, and tuning of a database will be maintained by DBAs.

One of the responsibilities of a DBA is to plan a contingency for disaster and ensure recovery of the database. 

They maintain the integrity of a database by using "backup and recovery".  They perform client/server connectivity and do "performance/tuning" to maximize availability and good response time for their clients.  They may use Oracle Enterprise Management tools to perform and monitor their tasks.

On the other hand, the developers use front-end tools, back-end tools and management tools to perform their tasks.

They develop applications to manipulate a database’s data.   Their application will query, insert, delete and update a record or records.

They use front-end tools such as "form builder," "report builder," and "graphics builder."

They use back-end tools such as "schema builder," "procedure builder," and "query builder."

They use project builder tools to manage and deliver their applications to their clients.

Good Luck!